Use the diagram below as a guide. Find a round light on a wall, or have another person
hold a torch. Stand with a ball such a basketball in front of the light. The ball should
be between the viewer and the light. Hold it up at shoulder height. The part of the ball
that the viewer sees will be completely in shadow (This is New Moon).

Slowly turn clockwise on the spot 90 degrees. Only the left half of the ball is lit
(This is First Quarter).

Turn another 90 degrees clockwise and the viewer should see all of the ball on their
side lit (this is Full Moon).

Turn 90 degrees again and the viewer should see the right side of the ball lit (This is
Last Quarter).